Take it from a retired Navy guy:
1) Russia is not only serious about re-starting aircraft carrier construction, but also serious in rebuilding and increasing quantity and quality of all of its Armed Forces.
2) Ditto with China as well. They especially want to increase the superiority of their Navy and make it a blue water Navy capable of challening us around the globe. They have watched us for many decades now stick our chest out and have our way around the globe with our Navy as the foremost, supreme instrument of diplomacy used to ensure we have our way. China is looking to neutralize and even negate that supremacy and "check" us whenever we seek to use that power in the future.
3) India is also "making waves" especially with its Navy. India has always, since shortly after WWII had some kind of aircraft carrier, so they've always dreamed of being a quasi military power or a superpower; they're close but no cigar yet.
4) You would think the European Union would band together all of its military resources, along with its vast potential financial and economic resources and become a military power to be reckoned with nudging America off of her pedestal being that all of those nations are becoming unified and are basically thinking and speaking as one. But they're still kind of sagging in different areas and have not reached total agreement toward being one unified nation; when they do, they will become the world's next premier economic, financial and military superpower.
While we (America) have our thumbs up our bung hole, and are desperately trying to hang on to our superpower status and are only playing superpower, the aforementioned nations are very very close to becoming powers and superpowers, especially militarily, in their own right. The time will come when we will no longer be number one. We need to really focus on what's important and quit spending recklessly where we don't need to spend; our power is being sapped financially and it's getting to the point where we can't afford to field an adequate military (all branches), and our peers, friends, and enemies are surpassing us militarily. The carriers are one of the most important "big sticks" that we have. If we lose the capability and/or the will to send these "big sticks" around the world where and when they are needed, our power will substantially come to nought, and then we will be ripe for a great challenge militarily from our adversaries.